A reclosable polymeric bag typically includes first and second opposing panels fixedly connected to each other along a pair of sides and a bottom bridging the pair of sides. The first and second panels are not fixedly connected along a mouth, which is formed opposite to the sealed bottom. Rather, the bag is provided with a reclosable zipper extending along the mouth of the polymeric bag. The zipper includes a male track and a female track. In reclosable polymeric bags of the type utilizing a slider to open the zipper, the male track typically includes a male profile and the female track includes a female profile. The zipper also includes first and second fins extending downwardly from the male and female tracks, respectively. The first and second fins are thermally fused to the inner surfaces of the respective first and second panels.
The male and female tracks are typically free of any plastic material above the male and female profiles in order to permit proper mounting and movement of the slider. The male and female profiles are releasably engageable to each other. When the slider is in a closed position, the male and female profiles are interlocked with each other. In response to moving the slider to an open position, the male and female profiles are disengaged from each other. Once the male and female profiles are disengaged from each other, access to the interior of the bag may be obtained by pulling the first and second panels apart at the mouth.
Opposite ends of the zipper are typically provided with end terminations. The end terminations may perform numerous functions, such as (a) preventing or inhibiting the slider from going past the ends of the fastener, (b) interacting with the slider to give a tactile indication of being closed, (c) assisting in inhibiting or preventing leakage from the bag, and (d) holding the fastener together and providing additional strength in resisting stresses to the bag.
End terminations may be in the form of a strap/clip that wraps over the top of the zipper. One end of the strap is provided with a rivet-like member that penetrates through the zipper fins and into a cooperating opening at the other end of the strap.
In the process of manufacturing the zippers, a long polymeric strip is fed through a manufacturing line. At different points along the manufacturing line, the strip is fitted with end terminations, sliders, and guide notches. The guide notches are cut into the zipper at the points where the strip will be cut to form individual bags. The guide notch is created by a punch mechanism that punches a hole in the male and female tracks and their respective fins. The guide notch is generally a U-shaped hole that starts at the male and female tracks and extends down into the respective fins.
The punch mechanism includes a punch housing and a punch. The housing forms a punch area, an input slot, and an exit slot. During the manufacturing process, the strip slides into the input slot, through the punch area, and out of the exit slot. At predetermined times, the strip stops, and the punch extends into the punch area, cutting the strip to form the guide notch. The guide notch is cut through the male and female tracks and extends down into the respective fins. The guide notch is generally U-shaped and includes a first edge of the male and female tracks and extends downwardly into the fins, a second edge that is generally perpendicular to the first edge, and a third edge that is generally opposite the first edge. After the guide notch has been formed, the punch retracts to its original position and the strip slides through to the next position to be cut.
As the strip advances through the punch housing, however, the second edge of the male and female tracks may not be in perfect alignment with the exit slot and, therefore, may catch on the slot. This slows, or may even stop, the advancement of the strip through the machine and can greatly affect the processing time. Also, if the lack of advancement is not caught immediately, it may cause the punch to form guide notches in incorrect spots along the strip, ruining the strip.
Therefore, there is a need for a punch mechanism that is able to cleanly punch a guide notch into the strip and also provide a timely and precise exiting of the strip from the punch area.